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Inverter Circuit 12V DC to 230VAC Sine Wave

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Wow, after having not reading my own thread for 2 weeks, it end up with so many discussions. Bravo.

For Arun > Is it possible for me to get the manual or reference book for UPS? I want focus in the battery charger and sine wave inverter study. My rough spec will be 12V 7Ah SLA battery charger(might be more than 1 piece) and for inverter is about 500W or more than that. If possible, i hope the reference book can cover every spec and explanation so i can see the difference from that.
And yeah, i'm from Malaysia. So anyway for me to get this?

For all>
Battery charger

For the battery charger, I would like to know more about the charging voltage, current and charging time. Is it efficient for us to use LM317 to charge the battery? As far as i know, to efficiently charge a SLA battery, we migh consider the charging voltage and temperature as well.

For the charging voltage, as i know, to charge a low energy SLA, we need to use cyclic charge 1st (2.35V-2.4V/cell) until the charging current drop to a minimum value (3% of the rated current), then we have to change the charging state to float charge (2.25V - 2.3V/cell)

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Hello Sasi !

Today, i was just going thru your Pcbs & Schematics in this thread, i felt there were inconsist with each other. ( hold a second, Don't get angry!)

what i mean is - the output mosfet section schematic shows only 33 Ohms gate resistors , but your Board shows Gate resistors + Diodes+ diode or resistors.

and also in the Oscillator section, in the schematic you have shown one diode, but on the board there are a Pair of diodes.

a final request,

your PCBs are helpful to any member who wud like to build an inverter, so can you post the Silk screen with the Component Values   instead of just Component outlines.



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Hello Sasi  :D

the big Diodes, capcitors, 220 Ohms -high wattage Resistor, all these components are used for Protecting the Mosfets from High Voltage Stress & Spikes from the Trafo.

if  u are not using them correctly,  the Mosfets are at risk.

since you have Vol- 19 of EFY Projects, there is a PWM Inverter Construction project by Mr. Bashin, using SG 3525, the author has used simple Setup to Drive  Mosfets without using BC 557s & BC 547s.

the Spike protection for mosfets looks good. :D

Did you try that circuit ? ???

here's the Circuit  ;D



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HI to all,i have build the 500w inverter and works perfectly i tested it to see its maximum capability and deliivered almost 700w from it,also if you need it more powerful dont use 2N3055 transistors but use 2N5886 as you gain about 40% more power on the whole,i took some pictures of the inverter and is posted on my website of stages in construction and how i designed the heatsinks as the sides,take a look at it on this adress:  http://inverter500.blogspot.com/  if you need help in construction im here to help.

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Thanks audioguru,well the heatsinks i made them from a piece of anuminium plate i got from a tool maker and cutted it 135mm by 135mm its thickness is 10mm,then inserted a 2n3055 in a piece of cardboard and cutted its outline with a scissors which i used as a jig to draw the transistors on the heat sinks.then i drilled the mounting h ;Doles and connection holes with a 4.5mm drill
the transformer i got it from an old plating equipment i found in a factory skip and was rated 615va.it works quite well all i had to modify in the circuit was that i installed a 7812 voltage regulator on the control board to keep stable voltage and instead of a resistor for the frequency resistor i used a pot for fine tuning of frequency.it is a litle heavy as a unit but i use it to powerr up my garage as there is no electricity where it is and made o box with abatery and a charger that i charge at home and connect it to the unit at the garage.next thing i want to add is a solar battery and a charge regulator and that would become a solar powerstation!

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  • 4 weeks later...
Here's an ebook I've found about inverters, in general, it does cover sinewave inverters but it doesn't show any schematic so you'll have to figure that part out for yourself.

My understanding is that there are 4 ways of designing a sinewave inverter:

(1) Use a resonant transformer - simple but yeilds a distorted sinewave.

(2) Build a low voltage inverter that uses a signal generator and class D amplifer to convert the low voltage AC and use a transformer to boost it to the mains voltage as audioguru was talking about.

(3) Build a DC-DC converter that boosts the low battery DC voltage to a higher voltage DC than the the required output, then use a signal generator and class D amplifier to convert it to AC.

(4) Use lots of transformers with their secondaries connected in series and h-bridges on the primaries to produce a sinewave with so many steps they blend together.
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